High-power diode lasers which emit a high power apply loads to the facets of the individual crystal layers up to the limit range. To increase the power which can be output from a diode laser, it is possible for two diode lasers to be monolithically integrated one above the other. For this purpose, corresponding layers are grown on top of one another. As described in U.S. Pat. No. 5,212,706, the contact between two diode lasers which have been grown on top of one another is produced, for example, by a highly doped tunnel diode which is reverse-biased. The tunnel diode is exposed to extreme levels of load with regard to the current intensity flowing through it and may be destroyed by the loads which are present. A further example of a tunnel contact is given in U.S. Pat. No. 5,679,963.
The laser diodes are usually grown on from a series of layers, it being possible for the individual layers to include different materials and consequently to have different lattice constants. The different lattice constants between adjacent layers lead to stresses, so that elastic energy is stored in the layer stack and forces act between adjacent layers. If the force acting between two layers is too high, lattice dislocations are formed in or between the corresponding layers, which may render the diode lasers unusable.
The object of the invention is to provide an improved contact between two diode lasers arranged one above the other.